The invention relates to a surfacing device for making substantially plane the top surface of a viscous material contained in a receptacle, and it also relates to a surfacing method using such a device.
The term xe2x80x9csurfacingxe2x80x9d relates to surface finishing, i.e. to the operation which consists in making plane the surface of a viscous material such as concrete or cement.
In the prior art, a surfacing operation is performed by hand with a tool that has a plane surface (a rule or a trowel), with the tool being moved by the operator horizontally and substantially parallel to the surface to be smoothed, the plane surface, e.g. the edge of the tool, penetrating a few millimeters into the material in order to level the top surface of the viscous material so as to make it plane. The operator assesses the appropriate circular, linear, or arbitrary motion and imparts it to the tool.
Such manual surfacing is thus not strictly reproducible, and gives results that are very unequal in which the quality is usually associated with the experience of the operator. Furthermore, it is not possible to perform such an operation within a hostile environment in which an operator should not be present, in particular in an environment that is radioactive.
An object of the present invention is to solve the drawbacks of the prior art by providing a device that enables the surfacing operation to be automated so as to make this operation reproducible and capable of being performed without an operator intervening in the proximity of the receptacle.
According to the present invention, this object is achieved by a surfacing device for making substantially plane the top surface of a viscous material contained in a receptacle having a bottom wall and a cylindrical vertical side wall whose top edge defines a circular opening, the device being characterized in that it comprises:
a moving assembly designed to be placed in an operating position relative to said receptacle, in which position said assembly is above said opening;
first motor means and a first guide system enabling vertical translation movement to be imparted to said assembly relative to said receptacle; and
variable-speed, second motor means and a second guide system enabling rotary movement to be imparted to a moving subassembly belonging to said assembly; said subassembly comprising:
a vertical shaft on the axis of said cylindrical wall when said assembly is in said operating position, the top portion of said shaft being secured to said second motor means; and
a rule connected to the bottom portion of said shaft, the rule being of length substantially equal to the radius of said opening and having a bottom surface presenting a horizontal longitudinal portion for smoothing the top surface of the viscous material, said rule penetrating through said opening into said viscous material during a first stage in which the first motor means are activated to lower said assembly, said rule being set into rotation during a second stage during which the first motor means are activated to cause said assembly to rise.
It will thus be understood that the first motor means make it possible to raise or lower the major portion of the device, including the rule which constitutes the surfacing tool, and that the variable-speed, second motor means make it possible to rotate the rule and the portion of the device which is secured thereto so as to perform a circular movement that performs smoothing in automatic manner.
Furthermore, combining the raising movement and the rotation of the rule during the second stage makes it possible to perform surfacing in a plurality of passes, and at regularly increasing heights, such that when the rule is no longer in contact with the surface all of the material has been uniformly distributed and there is no need to remove surplus material, and consequently no need to clean off any splashes.
In an advantageous disposition, said subassembly also includes an arm fixed to said bottom portion of the shaft and extending diametrically over said opening when in said operating position, one end portion of the arm being connected to said rule and the other end portion being connected to a balancing system ensuring that the longitudinal portion of the bottom surface of said rule is horizontal.
In another particularly advantageous configuration, said subassembly further includes a vibrator system connected to said rule so as to add vertical oscillatory motion to said rule during rotation thereof, and a damping system placed between the arm and said rule to avoid transmitting the vibration that results from oscillation of the rule to the remainder of said device.
In this case, and preferably, said vibrator system comprise a pneumatic vibrator secured to said rule and fed by a compressed air circuit comprising a compressed air source, an angled feed tube having an upstream segment connected to said source, a rotary coupling connecting the downstream segment of said tube to the top portion of said shaft, a longitudinal channel passing along said shaft, and a flexible tube connecting the bottom end of said channel to said vibrator, and said damper system has resilient studs.
The present invention also provides a surfacing method using the above-defined device and characterized in that it comprises the following steps:
said device is positioned in such a manner as to place said assembly in its operating position over the opening of said receptacle, the shaft lying on the axis of said receptacle, the rule being above a radius of said opening;
a first stage is performed during which said first motor means are activated to lower said assembly until said longitudinal portion of the rule has penetrated into said viscous material; and
a second stage is performed during which said second motor means are activated to set said rule into rotation and during which said first motor means are activated to cause said assembly to rise at least until said longitudinal portion of the rule has moved out from the viscous material.
In particularly advantageous manner, the said second stage is a stage during which said second motor means are initially activated to set said rule into rotation at a first speed of rotation, and subsequently said second motor means are activated to cause said rule to rotate at a second speed of rotation slower than said first speed of rotation.
The invention also provides the use of the surfacing device of the above type for a receptacle, preferably made of concrete, which contains said viscous material, preferably concrete, and at least one box containing contaminated waste for subsequent long-duration storage, where said viscous material was cast into said receptacle during vibration of a vibrating table which vibrates with vertical acceleration and on which said receptacle was retained.
The invention will be better understood and secondary characteristics and advantages thereof will appear on reading the following description of an embodiment given by way of example.
It should be understood that the description and the drawings are given purely by way of non-limiting indication.